SVN: force SourceSVN plugin in svn_call
SVN: force SourceSVN plugin in svn_call

When used with a child plugin (e.g. SourceWebSVN), the wrong plugin
basename is used, resulting in configured options (e.g. svnargs) to be
ignored.

We now push the current plugin to SourceSVN, to ensure the configuration
is retrieved properly

Fixes #186

dregad/source-integration,mantisbt-plugins/source-integration,make-all/source-integration,mantisbt-plugins/source-integration,dregad/source-integration,make-all/source-integration,dregad/source-integration,make-all/source-integration,mantisbt-plugins/source-integration